Wednesday, October 24, 2012

Finishing and testing portable hexbeam

Folding antenna by DL1ELU (links to multiple posts to share my experiences at the bottom of this post)

Okay, so that is what the kit I posted earlier has become: a hexbeam - a 6 band antenna (6-20m) with 2 elements per band. It took me about 2 days to build it using the kit designed and produced by DL1ELU (http://www.foldingantennas.com). He produces custom build plastic parts making this a very well built antenna (much much better than my home brew cobweb).DL1ELU has an eye for details. This is not only apparent from the antenna parts but also from the manual. Each and every step is described and comes with a tick box - so you know where you left off. This works very well for me as I tend to race things, ending up with making the wrong decisions, not measuring accurately or putting things together in the wrong order. No chance for mistakes here.

From the manual of DL1ELU

To give you an example of Christian's approach: he knows that it is difficult to measure a long piece of wire accurately. He thinks it might be a good idea to put a small plastic pin in the ground, use some copper wire and attach both your measuring tape and the wire to this pin. To support this idea he actually put a small piece of fibreglass and a piece of extra copper wire in the kit and shows you in pictures how to use them.Brilliant.Note that the kit really is a kit: everything needs to be handled, prepared, put together, etc. The plastic parts are still connected together, the way they came out of the mould. Reminds me of those little toy plane kits I had as a kid. That kept me busy for two days but without the normal frustration (thanks to the manual). It was a pleasant pass-time.

I am aiming to use the antenna in the CQ WW contest this weekend. Before today I was able to put the whole antenna together except for the elements. I did already add the support wires and the element clamps and I prepared all the elements (collection of wires of the right length combined into drivers and reflectors per band).

This morning was my only time slot for testing this antenna this week. So I started this morning with unpacking the folded antenna, adding the elements and getting the whole thing up in the air (using my home brew alu mast).

Alu mast attached to the car - pushed out to abt 9m (30ft)

Using my FT-817 as analyzer I quickly checked the SWR on all bands. It was really acceptable, <1.5 on all bands. I think the antenna can still be improved on a few bands (the dip is now outside the phone segment on several bands) but I did not have the time now to tweak the antenna - I wanted to do some on the air testing.

The first test I did is one to bring a smile to a ham's face: I fired up the FT-857 (abt 90W output) and listened around. I heard a couple of stations from Asia and Oceania. So I pointed the beam north-east and started calling DX on 15m. The first station to answer was Ben, ZL1CAH.

Imagine that!

I have never worked ZL using phone before (not counting an old 11m QSO 20 years ago). Ben was not very strong - an indication conditions were not super - but he gave me a 55 anyway.

Then I worked 2 JA's before I had to pack everything together and get back to my normal duties.

Nice sight: the result of hard work and a good kit

One test is not really statistically significant so I will have to do some more tests and probably some A-B with my tried and trusted HyEndFeds. Theory and gut feeling tell me however that this antenna is worth the hassle of bringing a larger mast and the folding and unfolding process if I want to hunt DX.About the folding: I still have to figure out how to get the unfolding done efficiently. Today was my first try with the folded antenna - without the elements but with the support wires. It took me 30 minutes to get the thing untangled. I am not looking forward to doing the same again now the antenna has an extra 80 meters of wires attached to it.